Conventional peanut and other nut butters or spreads consist of a mixture of solid nut particles, liquid oil, flavorants, e.g., a sweetener such as sugar, high fructose corn syrup or honey, and salt, and a stabilizer. Peanut butters typically contain about 50% oil and about 50% solids. Peanut butters containing these levels of solids and oil have good texture, spreadability and flavor.
For some applications, however, it is desirable to have a peanut spread which contains higher levels of solids. This may be the case, for example, when a high protein and/or reduced fat nut spread is desired. High protein and/or reduced fat nut spreads are typically prepared by increasing the level of solid ingredients present in the final product relative to the level of oil. Reduced fat peanut spreads, for example, typically comprise from about 58% to about 75% solids and from about 25% to about 42% oil.
Unfortunately, increasing the level of solids in the nut spread relative to the level of oil can have deleterious effects on the quality of the nut spread. For example, increasing the level of solids in a nut spread can increase the viscosity of the spread such that the spread is undesirably stiff (e.g., nonfluid). Indeed, spreadability or fluidity is highly sensitive to the oil content of the nut spread; the lower the oil content, the harder the product is to spread. The addition of non-nut solids also reduces the fluidity of the nut spread by creating a polymodal particle size distribution for the finished nut spread (reduced fat nut spreads desirably have a monomodal or bimodal particle size distribution). Increasing the level of solids in a nut spread relative to the level of oil can also adversely impact the texture of the nut spread. The solid particles create an undesirable sensation of grittiness upon mastication of the nut spread. Lastly, increasing the level of solids in a nut spread can adversely affect the flavor of the nut spread by diluting the peanut flavor.
Past attempts to provide nut spreads which have the combination of desirable fluidity, smooth texture and desirable flavor but which contain a high level of solids (e.g., greater than about 58%) have not been wholly successful. Efforts to reduce grittiness have resulted in a high viscosity spread. Moreover, attempts to reduce viscosity have resulted in nut spreads with less flavor compared to full fat peanut butters. A process taught by Wong et al. utilized a roll milling operation to prepare defatted peanut solids for use in a low fat peanut spread. See U.S. Pat. No. 5,079,027 issued Jan. 7, 1992. Another process taught by Walling et al utilizes extrusion roasting or a combination of roll milling and high shear mixing to prepare defatted peanut solids to be combined with undefatted peanuts in the preparation of a low fat peanut spread. See U.S. Pat. No. 5,230,919 issued Jul. 27, 1993. The use of defatted peanuts and intense processing conditions in these processes resulted in peanut spreads with inferior flavor compared to full fat peanut butters. Moreover, the roll milling and extrusion roasting processes taught by Wong et al. and Walling et al. are relatively capital intensive for a peanut manufacturing operation.
It is therefore an object of the present invention to provide a continuous process for preparing high protein and/or reduced fat nut spreads which have desirable texture (e.g., are not gritty) and fluidity and which have a nut flavor comparable to that of conventional full fat nut butters.
Co-pending U.S. patent application Ser. No. 08/136,524 (Wong et al), filed Oct. 14, 1993, also discloses a process for preparing high protein and/or reduced fat nut spreads which have desirable texture and fluidity and which have a nut flavor comparable to conventional full fat nut spreads. The process of the present invention is an improvement over the prior Wong process in several ways. First, the process of the present invention does not require that the Casson plastic viscosity of the nut spread mixture be adjusted to less than 30 poise before being pumped through the homogenizer. Instead, the homogenizer is operated at higher pressures (between 9,000 and 14,500 psig compared to less than 8,000 psig in the prior application). This makes the processing of the nut spread easier and less costly. Second, the mechanism for preparing the nut butters is different. In the prior Wong application, the viscosity of the nut butter actually rose after homogenization. This does not occur in the process of the present invention because of the higher solids concentration during homogenization (higher particle to particle sharing). Also, the cooling step of the process of the present invention contributes to certain flavor benefits that are recognized in nut spreads prepared according to the process of the present invention (e.g., gets rid of any off flavor that might otherwise result).